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 Post subject: Crossover point range
PostPosted: Thu Oct 12, 2017 9:50 am 
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Given a driver with response of say up to 2000hz and a recommended crossover at 1000hz, how far above 1000 would be acceptable? 1100? 1200? More or less?


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PostPosted: Thu Oct 12, 2017 9:57 am 
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Hard to guess given the little info you provided. What driver are you inquiring about? Do you have factory measurements and if not, can you perform your own?


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PostPosted: Thu Oct 12, 2017 10:35 am 
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if recommended frequency cut off is 1000hz. why would you want to go higher?
if they recommend 1000 hz. that mean that higher cut off will not sound good or give you trouble like big peek or drop in response, or distorsion.


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PostPosted: Thu Oct 12, 2017 10:40 am 
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But recommend at 1000hz with what order slope? We also have to take into consideration what this woofers is being paired with?


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PostPosted: Thu Oct 12, 2017 10:58 am 
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if you take for example. let say jbl 18 inche woofers like 2240, 41, 42,45 are all 1000hz highest recommended cut off point.
jbl never cut these higher then 500 hz. so they ALL NEED low mid range like a 8 inche. 10 inche or 12 inche lower mid range.to performe at their best.
so really recommended cut off is already stretching it to the limit. you are far better off going lower then. even much lower then that specific point.


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PostPosted: Thu Oct 12, 2017 11:07 am 
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The simple answer seems to be if it is 1000, stick with 1000. What about lower? 900, 800? Or is it still stick with 1000.

Basically I am looking at building a pair of frankensteins. Without actually getting crossovers made I seem to have a few choices, none of which seems to satisfy everything. I can cross the low end higher where the horn wants to be, I can cross the horn over lower where the woofer wants to be, I can use a different horn that crosses even lower than 1000, I can scrap the whole idea, or find a set of horns at 1000 hz.


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PostPosted: Thu Oct 12, 2017 11:16 am 
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You still need to look at the frequency plots of all drivers/horns that are to be used and then determine what is the best x-over (assuming they pair well) and at what slope. The woofer may have a large peak at 2khz so despite the recommended x-over of 1000hz, that peak still has to be dealt with. The recommendations from manufactures are not always the best.

The below example recommends a x-over at 2500hz. But looking at the plot 2.5khz is a good 5db down from 1000hz but also has a dramatic 12 to 15db peak just before 5Khz. It’s a good example that recommendation are not always the best.


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PostPosted: Thu Oct 12, 2017 12:22 pm 
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It also depends on the slope of the Xover.

A shallow (first order or 6db per octave) should be further from cone break up than a steeper Xover.

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PostPosted: Thu Oct 12, 2017 1:10 pm 
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In addition to all the points made, there's also a range of human hearing that's most sensitive (in a bad way) to the unwanted/audible effects of crossovers. I can't remember now but I think it's something like between 600-1800Hz?


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PostPosted: Thu Oct 12, 2017 1:46 pm 
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sthomas1049 wrote:
But recommend at 1000hz with what order slope? We also have to take into consideration what this woofers is being paired with?


The above is really key and you haven't provided enough information. If you are pairing with a horn, the size of the horn (in addition to the driver) can limit how low you can go (as well as what order slope). You also need to keep in mind any roll off or peaking in a driver response combined with an electrical crossover slope can create a different 'acoustical' slope that you need to integrate.

The crossover can essentially change the character of a speaker significantly and is really an art. Even the actual components themselves such as inductor types or capacitor types/brands can flavour a speaker reasonably enough. An electronic crossover and measurements can certainly get you in the ballpark of where you want to be as far as design goes, but may or may not be adequate for the final product. There may be many design options that 'work' and are 'proper' but you also need to spend time listening to several tweaks to settle on a final sound. Your ear and personal preference will help you in the end.


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PostPosted: Thu Oct 12, 2017 4:00 pm 
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Excellent reply! ............+1


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PostPosted: Thu Oct 12, 2017 4:09 pm 
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More important is the lower limit* of the driver you'll be crossing over to.

*I meant to say resonant frequency (Fs). Lower limit will be 2 octaves above Fs.

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Last edited by ripblade on Thu Oct 12, 2017 4:38 pm, edited 1 time in total.

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PostPosted: Thu Oct 12, 2017 4:14 pm 
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[quote="Sarchi"]In addition to all the points made, there's also a range of human hearing that's most sensitive (in a bad way) to the unwanted/audible effects of crossovers. I can't remember now but I think it's something like between 600-1800Hz?[/quote

And that is smack dab in the midrange.


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PostPosted: Thu Oct 12, 2017 4:51 pm 
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Have you considered using a midrange driver?

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Alec


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PostPosted: Thu Oct 12, 2017 4:55 pm 
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I'd say you're looking for the right crossover for the speaker, not just the driver. Build what seems reasonable and fine tune it with the crossover. Having screwed around with this I would bet it's not likely you'd nail the crossover in the first shot, judging from the nature of your question really.


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